Tire building drums for applying a tread and belt package onto a green tire carcass are known. The tire building process generally has a stage one assembly of a tire carcass made of air impervious inner layer, a pair of beads, an apex, and a reinforcing ply extending between, and wrapping around, the beads to form ply turnups. This unvulcanized structure may also have sidewall rubber and outer rubber components, such as gum strips, chafers, or chippers added to the cylindrically shaped green tire carcass.
In a second stage, the green or uncured cylindrical carcass may be taken to a separate tire building drum wherein the beads are locked onto the drum, moved axially to a proper bead width spacing, and the carcass is toroidaly shaped by expanding the carcass using an inflatable bladder which allows the carcass to assume a shape more closely approximating a finished tire. At this point, belt or breaker reinforcements, such as steel cord reinforcement belts, may be applied onto the carcass. Typically, adjacent belt layers have cords oppositely oriented. Once the belt structure is applied, a layer of tread rubber may be added to complete the assembly.
These building drums may be capable of moving the center section radially outward while moving the beads axially inward. A green tire may also be built with a single drum assembly thereby allowing the ply turnup to be made as the tire ply is held vertically in the bead regions. Another second stage tire building drum may allow a relatively small tire carcass having a large diameter to be made. A machine may be specifically adapted to construct motorcycle tires of a diameter of 16.0 inches, 16.5 inches, and 17.0 inches of different axial bead widths.